Two-Dimensional Metal Nanostructures: From Theoretical Understanding to Experiment

Abstract

This paper reviews recent studies on the preparation of two-dimensional (2D) metal nanostructures, particularly nanosheets. As metal often exists in the high-symmetry crystal phase, such as face centered cubic structures, reducing the symmetry is often needed for the formation of low-dimensional nanostructures. Recent advances in characterization and theory allow for a deeper understanding of the formation of 2D nanostructures. This Review firstly describes the relevant theoretical framework to help the experimentalists understand chemical driving forces for the synthesis of 2D metal nanostructures, followed by examples on the shape control of different metals. Recent applications of 2D metal nanostructures, including catalysis, bioimaging, plasmonics, and sensing, are discussed. We end the Review with a summary and outlook of the challenges and opportunities in the design, synthesis, and application of 2D metal nanostructures.

Ultrathin Rh Nanosheets with Rich Grain Boundaries for Efficient Hydrogen Oxidation Electrocatalysis

“…Electrocatalysis plays a crucial role in facilitating the widespread utilization of renewable energy sources in the future. − However, the reliance on Pt-group metals as catalysts for renewable energy applications remains predominant. , To reduce the dependence on scarce Pt-group metals, substantial efforts have been devoted to searching for alternative electrocatalysts with high intrinsic activity and abundant active site exposure. − The design of an architecture electrocatalyst has been recognized as an effective approach to achieving this goal. In particular, two-dimensional (2D) ultrathin nanosheet (NS) materials have garnered considerable interest due to their distinctive structural advantages. − The 2D nature of these NSs provides a large exposed surface area, allowing for more active sites for reactant adsorption. − Moreover, their atomic thickness facilitates rapid diffusion of reactant molecules and efficient charge transfer, minimizing mass transport limitations and enhancing reaction kinetics. , Besides that, a large portion of the metal atoms are readily available on the surface of ultrathin 2D NSs, enabling them to actively participate in the catalytic reaction and maximize atomic utilization . These advantageous features endow ultrathin 2D NSs with immense potential as highly efficient electrocatalysts.…”

Large-area arrays of epitaxially aligned silver nanotriangles seeded by gold nanostructures

“…Among these, nanostructures exhibiting a two-dimensional planar morphology have attracted widespread interest in terms of the properties they express, the applications forwarded, and the underlying mechanisms that lead to the emergence of a thermodynamically unfavorable geometry with a high surface energy. [3][4][5][6][7] Within this classification, triangular nanoplates stand out as the most prominent planar structure due to (i) a size-dependent localized surface plasmon resonance (LSPR) that extends from visible wavelengths into the infrared, 8 (ii) atomically flat (111) surfaces suitable for precise functionalization, 9 and (iii) large localized electric field enhancements occurring at their sharp tips or between two nanotriangles arranged in a bowtie configuration. 10 In this regard, Ag nanotriangles are far superior to those composed of more lossy metals such as Au and Cu.…”

“…3,4,12 The mechanistic requirements for Ag nanoplate synthesis center around the establishment of symmetry breaking controls able to steer growth along a two-dimensional pathway even though it is contrary to the centrosymmetric nature of its face-centered cubic (fcc) crystal structure. [3][4][5][6] It is widely accepted that symmetry breaking is facilitated by the emergence of stacking faults in the seed formation process. [13][14][15] These stacking faults, which are disruptions to the stacking order along a h111i-axis, break the ABCABC.…”

Continuous Phase Regulation of a Pd–Te Hexagonal Nanoplate Library

“…Two-dimensional (2D) nanomaterials exhibit fascinating physical, chemical, and electrical properties − and wide applications in various fields, such as biomedicine, − catalysis, − surface-enhanced Raman scattering, − and sensing, − due to their electronic confinement, ultrahigh specific surface area, and high exposure of surface atoms. In particular, 2D noble metal nanomaterials represent a distinct group of 2D materials.…”

“…4 Te HNPs (c-Pd 4 Te HNPs) with the slightest increased d Pd-a-Pd . Density functional theory (DFT) reveals that the d Pd-a-Pd of different Pd−Te HNPs is a vital structural descriptor for the OH* adsorption energy barrier for the ORR, where an increment in d Pd-a-Pd can significantly improve the ORR reaction activity owing to accelerated OH* desorption, demonstrating the role of phase control in optimizing metal noble metal-based nanocrystals for catalysis.…”